AB0060 ANALYSIS OF THE HUMAN GUT MICROBIOME AND NUTRITION PATTERNS IN RHEUMATOID ARTHRITIS
Authors: J. Schirmer, K. Schlicht, C. Knappe, K. Türk, D. Schulte, K. Hartmann, U. Settgast, A. Franke, S. Schreiber, B. Hoyer, M. Laudes
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> The association of the gut microbiome with obesity and metabolic diseases as type 2 diabetes (T2D) as well as the influence of environmental factors like nutrition on its composition is well established. In addition, recent studies<sup>[1]</sup> described the composition of gut microbiota to be altered in inflammatory rheumatic diseases highlighting a pathogenetic link between the microbiome and autoimmune joint diseases. <h3>Objectives</h3> The aim of this study was to analyze food intake and the composition of the gut microbiota in rheumatoid arthritis (RA) in comparison to healthy controls (adjusted for metabolic conditions known to influence the gut microbiota composition). <h3>Methods</h3> A subset of the FoCus (Food chain plus) cohort (a cross-sectional survey of the general population in northern Germany) with RA and matched controls without RA (matched for age, gender, body mass index and diagnosis of Type 2 Diabetes mellitus [T2D]) was investigated regarding their nutrition patterns and gut microbiome in a case-control analysis. Nutrition patterns were derived from Food Frequency Questionaires (FFQ) and analyzed by hierarchical cluster analysis. The gut microbiota composition was analyzed by 16S rRNA gene sequence data clustered into operational taxonomic units (OTUs). Microbiome composition was analyzed by alpha- (phylodiversity, Shannon index, Chao index) and beta-diversity measures (Bray-Curtis distance, Jaccard index) and by hurdle-models. <h3>Results</h3> We identified n = 94 individuals with RA and n = 94 matched controls (mean age 57 years, SD 12.9; mean BMI 31.1, SD 8.9). Interleukin 6 was significantly higher in the RA group compared with controls (p=0.012), while no differences were observed between groups for HOMA-Index, CRP, lipoprotein (a) or triglycerides. Nutrition data from FFQs was used in a hierarchical cluster analysis, resulting in two main clusters (the second one defined by a significantly higher intake of vegetables, fruit and dairy products). Nutrition clusters did not differ significantly between RA cases and controls (p=0.228). When comparing the composition of the intestinal microbiota between RA patients and controls (adjusted for nutrition cluster and IL-6), significant differences in the beta-diversity were detected using Bray-Curtis distance (p=1.82e-9) and Jaccard index (p=1.82e-9). Hurdle model analysis of the core measurable microbiome identified three candidate species OTUs (Flavonifractor and 2x Blautia). No significant differences in alpha diversity was observed when analyzed by species richness (p=0.9), Shannon (p=0.3) and Chao index (p=0.6). <h3>Conclusion</h3> Participants suffering from RA had significant differences in the composition of the gut microbiome compared to controls matched for age, BMI, gender and T2D after adjusting for nutrition patterns and IL-6. Investigating differences in the functional capacity of the altered gut microbiome in RA may better characterize a possible link of gut microbes to the development of RA. <h3>Reference</h3> [1]Chu XJ, Cao NW, Zhou HY, Meng X, Guo B, Zhang HY, Li BZ. The oral and gut microbiome in rheumatoid arthritis patients: a systematic review. Rheumatology (Oxford). 2021 Mar 2;60(3):1054-1066. doi: 10.1093/rheumatology/keaa835. PMID: 33450018. <h3>Acknowledgements</h3> The project was supported by the German Society for Rheumatology (Deutsche Gesellschaft für Rheumatologie/ DGRh) and the Competence Network Rheumatology (Kompetenznetz Rheumatologie)/ DGRh Research Initiative 2020. <h3>Disclosure of Interests</h3> Jan Schirmer: None declared, Kristina Schlicht: None declared, Carina Knappe: None declared, Kathrin Türk: None declared, Dominik Schulte: None declared, Katharina Hartmann: None declared, Ute Settgast: None declared, Andre Franke: None declared, Stefan Schreiber: None declared, Bimba Hoyer: None declared, Matthias Laudes Speakers bureau: AstraZeneca, Lilly, Bayer, Consultant of: AstraZeneca, Lilly, Bayer.